Spectroscopic properties of ytterbium, praseodymium-codoped fluorozirconate glass for laser emission at 3.6 μm

Excitation of the F-2(7/2) -> F-2(5/2) transition of the Yb3+ ion in Yb3+, Pr3+-doped fluorozirconate glass at 974 nm results in efficient excitation of the (1)G(4) level of Pr3+ ion that in turn emits in the middle infrared at similar to 3.6 mu m. The energy transfer (ET) process Yb3+(F-2(5/2)) -> Pr3(+)((1)G(4)) is assisted by fast excitation migration among the Yb3+ ions. An upconversion process involving ET from the F-2(5/2) level to the (1)G(4) excited state populates the P-3(0) excited state that produces emission at 481, 521, 603, 636, and 717 nm. A study of the behavior of the fluorescence from the (1)G(4) level at 1325 nm and from the P-3(0) level at 603 nm allowed the estimation of the ET rate constants for the processes involved after short-pulsed laser excitation at 974 nm. A rate-equation model was employed to evaluate the population inversion relating to the (1)G(4) -> F-3(4) transition of the Pr3+ ion at 3.6 mu m under continuous wave pumping. (C) 2013 Optical Society of America